1. Field of the Invention
The present invention relates generally to mechanical diagnostic gauge devices for measuring physical quantities in industrial applications, and more particularly, to a portable diagnostic gauge device that displays the magnitude of physical quantities in industrial applications and has an electroluminescent panel that illuminates the dial in dark or low light areas for improved visibility of gauge readings.
2. Description of Related Art
Industrial mechanical/analog diagnostic gauges are required and used for reading and displaying a variety of important measurements that must be periodically monitored to facilitate quality control and safety. However, in many industrial applications these gauges are located in areas where there is little to no light and, or inadequate space, making it difficult, if not impossible, to reliably read measurements. It is especially difficult to accurately read these gauges in dim lighting when it is situated several feet from the operator or in a cramped space. These obstacles increase the risk of inaccurate or neglected readings.
A variety of devices and methods are known that proffer to address and resolve these problems, but they have realized little to no practical success or acceptance. These attempts include the use of auxiliary lighting, luminescent materials and reflective materials that require an external source of light and complicated electronics, such as piezoresistive transducers, as disclosed in U.S. Pat. Nos. 6,415,672, 6,394,977, 5,839,810, 4,561,042, 3,503,365, 3,219,008, 3,094,970 and 2,272,806. For instance, U.S. Pat. Nos. 2,272,806 and 3,503,365 disclose the use of external or auxiliary light sources for illuminating gauges. As noted, external light sources dramatically increase cost and complexity in design, requiring additional wiring, equipment and time. Furthermore, external light sources reduce the portability of the diagnostic gauge device. Providing a gauge with contrasting colors in the construction of the dial has also been suggested. The contrasting colors, however, require light to see and thus do not allow for the recording of accurate measurements in no light conditions.
Other attempts to improve gauge visibility proffer the use of luminescent and reflective materials to construct the face, the face markings and the hands, such as disclosed in U.S. Pat. Nos. 4,561,042 and 6,415,672. These luminescent materials absorb energy from both ambient and direct light. The ambient or direct light causes the luminescent material to charge, after which the material can glow. Luminescent display gauges are not suitable for applications that are constantly in dark. Situations that do not allow for exposure to any direct light require an external ambient light source in close proximity to the gauge in order to charge the luminescent material. The need for an external ambient light source dramatically increases costs. Furthermore, the need for an external light source reduces the portability of the diagnostic gauge and the ease of replacing such devices.
Diagnostic gauges are not only limited to industrial applications. In recent years, a need for small and reusable diagnostic gauges for medical devices has grown. Specifically, there is a need for pressure gauges to be used in syringes that are used to inflate angioplasty balloons. One major requirement is the need for a device that can withstand the harsh temperatures and chemicals present in the sterilization process to enable a reusable pressure gauge. Due to the requirement of repeated use, a piezoresistive transducer is used instead of a bourdon tube to measure the fluid pressure, as disclosed in U.S. Pat. No. 6,394,977. Furthermore, an analog mechanical display device, utilizing a stepper motor is used and can withstand the elevated temperatures of the sterilization procedure. The stepper motor is sent digital signals representing the actual measurements from a microprocessor. This microprocessor is powered with a battery contained within the gauge housing. As a result of the applications in medical devices used during surgery it once again becomes difficult to reliably read the measurements of the syringe pressure gauge.
Another attempt involves the use of an infrared emitter and receiver to present data on a separate, easily viewable, display. This solution adds many components, which dramatically increase the cost of the pressure gauge. Another attempt uses an internal illumination system such as the electroluminescent display system of watches. Many watch illumination systems utilize an electroluminescent material as a source of ultraviolet (UV) light. Indicators on the watch face are covered with a phosphorescent material. Upon exposure to UV light emitted from the electroluminescent material, the phosphorescent indicators emit visible light through a process known as fluorescence. As the efficiency of electroluminescent materials has improved, many watches now utilize electroluminescent materials to emit visible light, thus illuminating the watch face.
Electroluminescent layers have also been used to illuminated industrial diagnostic gauges, as disclosed in U.S. Pat. Nos. 6,394,977, 5,839,810, 3,219,008 and 3,094,970. Usually, an electroluminescent layer can be either bonded or printed onto a support plate. A clear dial face is applied over the electroluminescent layer to create a readable illuminated dial. Electrical contacts are made through an electrically conductive layer, which connects the electroluminescent layer to electrical drive and control components located on the backside of the support plate. The electrical contacts are either made using a through-hole design or a wrap around design. The attachment of the electrical components to the back of the support plate makes it difficult to access the circuitry to perform a variety of functions, such as activating an on-off switch, changing batteries, controlling the illumination of the dial, performing maintenance or making other adjustments. These devices also are powered by bulky external power sources that further decrease the portability of the device.
Regardless of the application, industrial, medical or otherwise, the ability to accurately read measurements displayed in analog is necessary and predicated on the ability to see the face of the gauge regardless of the level of ambient light. Unfortunately, the aforementioned attempts fail to disclose or suggest a mechanical/analog diagnostic gauge adapted for reliable visibility in dim to dark conditions without compromising size, costs, adaptability or portability. The instant invention fills this void in the related art with a diagnostic gauge that employs a highly efficient electroluminescent display that is compact, portable and interchangeable as contemplated by the instant invention disclosed herein.